Wal-Mart’s resources/sources of competitive advantage

What are Wal-Mart’s resources/sources of competitive advantage? Are they sustainable? How have they delivered value? What are the important principles that the company uses in managing its relationships with suppliers? What alternative strategies might suppliers be able to employ to ensure their continued viability as a Wal-Mart supplier? What are the best practices that the company has been able to transfer from its home operations to its ventures abroad? What are the practices that have not worked? What is your prognosis for the future success of Wal-Mart in the U.S. and abroad? What changes does the company have to make to ensure continued success?